1. Field of the Invention
The present invention pertains to a vapor recovery system. More particularly, the present invention pertains to a system for the recovery of vapors from volatile liquids.
2. Description of the Prior Art
Motor vehicles are generally provided with liquid fuel at service stations equipped to pump such fuel from a fuel storage supply to a fuel tank located within the vehicle. The fuel is generally passed through a fuel pump to a hose which terminates in a liquid dispensing nozzle. The nozzle dispensing outlet is connected to or inserted into the vehicle fuel tank inlet, and the pump and nozzle are actuated in order to cause delivery of fuel from the service station storage to the vehicle fuel tank.
Most fuel nozzles in use include means for maintaining the nozzle in a fuel-delivery condition without the necessity of an attendant holding the nozzle in such condition. Such automatic nozzles include means to cut off the flow of fuel therefrom when the vehicle fuel tank has reached its full condition. The fuel passes through a fuel filler pipe on the vehicle tank in passing from the nozzle to the vehicle fuel tank. Such fuel is normally supplied at a rate in the order of two to fifteen gallons per minute. As a consequence, considerable agitation of the fuel may take place as the fuel is received in the vehicle fuel tank.
This agitation frequently results in a splash-back of fuel through the fuel filler pipe of the vehicle. The splash-back is often so great that fuel spills onto the ground and onto person in the vicinity of the vehicle. The splash-back is particularly heavy when the fuel tank has reached its full condition and an automatic nozzle is caused to cut off. The fuel spilling on the ground creates a hazardous and undesirable condition. Not only does it present a danger of fire but also its evaporation results in pollution of the air.
In addition, and even more importantly, as fuel is being supplied to a vehicle, fuel vapor escapes from the vehicle fuel tank filler pipe, and this vapor adds to the air pollution. Air pollution is increasingly becoming a cause of concern. Hydrocarbon vapors represent a major contribution to air pollution and form photochemical smog. Such polluted air is an irritant to human respiratory and lachrymal systems. While the reduction of the fuel delivery rate helps to reduce the escape of liquid fuel caused by splash-back, it does not prevent escape of fuel vapors and, in fact, because of the longer time required to fill the vehicle fuel tank, the reduction of the delivery rate may increase the escape of fuel vapors during the filling of the tank.
In an attempt to reduce the pollution problems caused by the release of hydrocarbon vapors to the atmosphere, various refrigeration and other systems have been developed for the recovery of such vapors. However, such systems are extremely expensive. In order to prevent any release of hydrocarbon vapors to the atmosphere, such systems must cool the vapors to temperatures low enough to condense all the vapors. Even at such low temperatures all of the hydrocarbon vapors may not be condensed due to a failure of the vapors to adequately contact the refrigeration cooling means such as cooling fins, etc. An additional problem unsolved by such systems is the removal of noncondensables such as air from the system, while assuring that no hydrocarbon material will escape. The purpose of this invention is to provide an improved vapor recovery system.